Defect Parameters Research Articles

机械损伤对蓖麻种子发芽影响试验及损伤检测研究

To study the types of mechanical damage for castor seeds and their effects on germination, the image processing method was applied to detect the damage affecting germination. Two typical varieties of castor were selected for test. The type of mechanical damage of castor seeds was taken as the factor, the germination rate and germination vigor index were selected as indicators for one-way analysis of variance. The effects of mechanical damage on the germination of castor seeds were analyzed. Different algorithms were applied to extract the features of cracks and seed shell missing, and the corresponding defect parameters were calculated. The results showed that the effects of mechanical damage on the germination rate, germination potential, germination index, and vigor index of castor seeds were significant. The endosperm damage seriously affected the activity of castor seeds and seriously hindered seed germination. According to the analysis of the shell, some castor seeds cracked or there was incomplete shell damage at the same time, the internal endosperm being also damaged. The actual crack length was compared with the length measured by the ultra-depth of field microscope, which found that the margin of error was about 25% and the better error was 10%. Through the morphological processing, it could completely extract the characteristics of castor seed image without seed shells. The error between the extracted feature area and the measured object area function of the super depth of field microscope is about 10%.

Copper defects for CO2 electrocatalysis toward a specific multicarbon product

Defects on Cu surfaces are created to tune the selectivity of CO2 electroreduction toward C2+ products. However, mixed defect structures and the coexistence of defect-induced geometric and electronic effects impose a grand challenge to correlate the defect type with product selectivity. Here, we explore the underlying defect parameter determining selectivity.

OPTIMAL FAULT DETECTION OF RIVER SHIP HULLS

The issue of determining the reliability of the hulls of inland and river-sea-going vessels after a known number of years of operation under given condition is considered. It is accepted that fault detection of a ship’s hull is a survey, measurement and evaluation of defects in each element of the ship’s hull in order to establish the methods and scope of repairs that ensure its reliable operation until the next regular survey under specified operating conditions. It is shown that the volume of residual thicknesses can be significantly reduced using the statistical data on wear rates presented in the Rules of the Russian River Register. At the same time, the reduction in the scope of measuring the parameters of defects retains the probability of detecting all defects of the hull elements to the level of 0.95, and the probability of failure-free operation of the hull until the next survey, after the elimination of the identified defects will be at least 0.95. A form of table for processing the values of the residual thicknesses of all elements in the inspection report and instructions for filling it out are given. Explanations for using the results of measurements and calculations at determining the technical condition of certain elements in the group and the ship’s hull as a whole are given. The last column of the table indicates the method of eliminating the defect of an element and groups of elements, and in the conclusion of the inspection report, the method of repair and its scope for the entire hull of the ship providing a suitable assessment of the condition after repair are indicated. The main advantage of this paper, in difference from the previous studies of the authors in this area, is that user-friendly (the designer of the defect report tables) nomograms, which allow you to reduce the number of measurements of the residual thicknesses of hull structure elements in the online mode, have been created. The performed study, allowing you to reduce the number of measurements while guaranteeing the reliable operation of the ship’s hull, will let the shipowner to reduce the cost of repair work by reducing the number of days of ship standing on the slipway (in the dock). In addition, the ship repair company will be able to free up its production facilities for the purpose of their subsequent loading with other ship repair or shipbuilding orders, which will increase the efficiency of their activities.

Effect of Defects Parameters of Welded Joints on Fatigue Life using Finite Element Analysis

The present investigation's main goal is to assess butt joint and T-joint plates containing misalignment, undercut and porosity welding defects by studying the influence of the defect’s parameters on the fatigue life. The fatigue life is predicted using ANSYS ver. 19 Software. The results of finite element analysis are used in the regression analysis to find relationship between the fatigue life and defects parameters. The findings demonstrated that finite element modeling and the pervious published experimental tests were in good agreement with maximum error percentage 4 %. The fatigue life differed substantially depending on the defect’s parameters.

Structural behavior of damaged reinforced concrete beams under static cyclic loading

Bridges are regarded as one of the most important components of transportation infrastructure. More and more repairs, inspections, alterations, and construction processes are required to maintain safe usage due to increasing travel demands in addition to bridge infrastructure aging. In this paper, we will discuss the experimental investigation using five reinforced concrete beams to evaluate the effect of making damage to experimental beams under static cyclic loading to investigate their ductility and energy dissipation. The defective parameters taken into consideration in the experimental program were the gap in the concrete mold and mild steel at the middle bottom reinforcement. All tested specimens had the same cross-sectional dimensions. The concrete dimensions of the beams were 200 mm in width and 300 mm in height, and the beam's length was selected to be 2200 mm, having a clear span of 2000 mm between the supports, they were tested in positive bending using a 3-point bending load system. According to the results, when (RC) beams were subjected to any of the mentioned types of damage, they showed a significant decrease in ultimate capacities ranging from 3.03% to 19.31%. The ANSYS model shows an average difference with the experimental program within 4 % as an acceptable agreement.

Influence of Form Defect on the Mechanical Behavior and Stress Intensity Factor of Shrink-Fitted Thick-Walled Cylinders

In this research work, the finite element software, ABAQUS is used to study by simulations the influence of form defect on mechanical behavior of a shrink-fitted assembly presenting internal radial cracks. Under the action of contact pressure induced by the tightening between two cylinders, these cracks resulting from incorrect assembly operations or materials elaboration defect, can be harmful to the assembly. Various simulations were carried out in two modeling cases, taking into account the geometric parameters of defect (amplitude Df), of cylinders (thickness t) and of cracks (length a, ratio a/t). Another important parameter such as the tightening was also considered in the modeling. The first modeling relates to the case with defect, external cylinder presents an oval (elliptical) form defect and internal radial cracks. The other concerns the perfect equivalent case (without form defect). The comparison of results obtained by two models shows that form defect modifies the uniformity of equivalent stresses distribution in cylinders and increases the value of stress intensity factor (SIF) KI in cracks. Defect amplitude and tightening significantly influence the value of equivalent stress and that of stress intensity factor (SIF) <i>KI</i>.

Sensitivity analysis of nonlinear frequency response of defected structures

The computation of the steady-stateresponse of large finite element discretized systems subject to periodic excitations is unfeasible because of excessive run time and memory requirements. One could in principle resort to reduced order models stemming from the high fidelity counterparts, which typically require a solution time orders of magnitude smaller. However, when many simulations are required, as in the case of parametric studies, the overall effort could be still significant and the analysis process could be severely hindered. In this work, we propose a sensitivity approach to assess the influence of model parameters on the nonlinear dynamic response. As opposed to the costly evaluation of reduced order solutions over a range of excitation frequencies and model parameters, the sensitivities of a nominal response allow one to approximate the dynamic response by a simple evaluation of an expansion in the directions spanning the parameter space. Special care must be taken on the closure equation that needs to be appended to the system of equations stemming from the harmonic balance method. We discuss the limitations of the current constant frequency approach and propose an improvement. We demonstrate the merits of the proposed approach on a micro-electro-mechanical system affected by parameterized manufacturing defects. Leveraging from a previous contribution, the nonlinear response and the sensitivities are obtained from a reduced order model which is analytical in the defect parameters. Our procedure is able to deliver accurate probability density functions of quantities of interest (e.g. nonlinear resonance peaks, triple solution bandwidth, etc) against statistical distributions of manufacturing defects at negligible computational cost.

Assessment of the Technical Condition of High-Voltage Insulators during Operation

During the operation process of high-voltage insulators, the characteristics of assessing their technical state are evaluated by using remote contactless monitoring and by subsequent forecasting of their residual life based on the developed set of diagnostic parameters of critical defects. Special attention is paid to the challenges of the practical application for remote contactless monitoring of high-voltage insulators’ current operating state. Measurements of characteristics for partial discharges on high-voltage insulators with various types of critical defects taken by electromagnetic and acoustic sensors are described. Based on the measurements, it was found that the unusual properties of the PD begin to manifest themselves starting from the intensities q ≥ 1.5–2 nC, and their maximum intensity can reach 5–7 nC. Up to PD intensities q ≤ 3 nC, most parameters of PD characteristics measured by electromagnetic and acoustic sensors correspond with an accuracy of 70–90%. It was found that for small defects with sizes d ≤ 300 μm in HVI, the PD intensity does not exceed 100 pC and depends little on the size of the defect. However, with an increase in the size of defects above 0.4–0.6 mm, a sharp rise in the intensity of the emerging VLPD begins.

Investigating the Combined Effect of Multiple Dent and Bump Faults on the Vibrational Behavior of Ball Bearings

The rolling element bearing is a fundamental component of any rotating machinery. During operation, wear debris and lubricant impurities create dents and bumps on the bearing raceway surfaces. Such localized defects produce transient vibration impulses at one of the bearing characteristic frequencies. Having a combination of multiple types of point defects on the raceway results in superimposed vibration patterns, which reduce the ability to recognize these defects’ effects. In this paper, a 6-DOF dynamic model is developed to accurately investigate the vibration characteristic of a ball bearing with a multipoint defect comprising a dent and bump on its raceway surface. The model considers the effects of time-varying contact force produced due to defects, lubricant film damping, bearing preload, and the inertia effect of rolling elements. The simulation results reveal the vibration behavior of multipoint defect bearings. In addition, bearing vibration response is affected by the number of defects, the angle between them, and the type and size of each defect. Furthermore, it is challenging to predict bearing defects parameters such as the numbers, types, sizes, and angles between adjacent defects from acceleration signal analysis without jerk signal analysis. The validation of the model is proved using signals from the Case Western University test setup.

Performance Analysis Using Air Gap Defected Through Silicon Via: Impact on Crosstalk and Power

In the recent past, various fabrication-related defects such as electromigration-induced open/short faults, interfacial cracks, and thermal stress-induced leakage problems in through silicon via (TSV) have a major impact on the reliability and performance of a TSV-based 3-D integrated circuit (IC). Considering these facts, this article for the first time provides the equivalent resistance-inductance-conductance-capacitance (RLGC) modeling and performance analysis of air gap-defected TSVs in comparison with defect free vertical interconnect at 7 nm technology in order to address reliability concerns. Considering different manufacturing imperfections such as air cracks and void holes, the analytical equations are derived using defective parameters to analyze the feasibility and reliability of defected TSVs. Using a driver-via-load (DVL) setup, an equivalent T-type electrical modeling of cylindrical TSV is proposed considering the impact of different forms of air-cracked defects. Therefore, the propagation delay, power dissipation, power delay product, peak noise, and dynamic crosstalk are analyzed using a carbon nanotube field effect transistor (CNTFET) driver. Encouragingly, considering a partial air-cracked TSV, the peak noise is improved by 4.83% approaching toward defect-free condition.

Study on the interface defects of eco-friendly perovskite solar cells

Because of the rapid improvement of perovskite (PSK) solar cells (PSCs), they are considered the most promising photovoltaic devices nowadays. This improvement is mainly observed in the lead (Pb)-based PSCs, though Pb is a highly toxic material. Due to this toxicity, Pb-free perovskites have drawn considerable attention as the substitute for Pb-based perovskites. Performances of these Pb-free PSCs depend on the interfaces between the perovskite layer and electron transport layer (ETL) and between the perovskite absorber layer and hole transport layer (HTL). This research focuses on the investigation of these interfaces in different PSCs, in which MASnI3, MAGeI3, and Cs3Bi2I9 perovskites are used the absorber layer. The effect of defect density, defect position, and the capture cross-section area of electrons and holes for these interfaces on power conversion efficiency are considered in this study through simulation conducted by the SCAPS-1D simulator. A significant effect of defect density in interfaces has been observed. Deep level traps have been identified as one of the performance degradation reasons. On PCE, the effect of ETL/PSK interface properties is much more significant than the PSK/HTL interface effect. Simulated results would enlighten the researchers to choose the perfect Pb-free perovskite for solar cells that will show greater tolerance against interface defects. Besides, these findings will be helpful in considering the optimum values of interface defect parameters of various types of practical PSCs.

Deep Learning Extraction of the Temperature-Dependent Parameters of Bulk Defects.

Bulk defects in silicon solar cells are a key contributor to loss of efficiency. To detect and identify those defects, temperature- and injection-dependent lifetime spectroscopy is usually used, and the defect parameters are traditionally extracted using fitting methods to the Shockley-Read-Hall recombination statistics. In this study, we propose a deep learning-based extraction technique that is based on an alternative representation of the lifetime curves: lifetime mapping in the temperature and minority carrier concentration space. The deep learning approach successfully predicts all the defect parameters while addressing one of the main limitations of the traditional approach of locating the defect in the energy spectrum, which usually outputs two possible solutions. Furthermore, the approach is applied to temperature-dependent defect parameters where the traditional approach is not applicable, achieving satisfying levels of prediction of the defect parameters. Image representation and deep learning have the potential to bolster solar cell characterization techniques by extracting more insights from the characterization data.

Review of Medicinal Plants Acting as Vrushya (Aphrodisiac Activity) w.r.t Bhavprakash Nighantu

Ayurveda is an ancient science and it has a Holistic approach. There are eight branches of Ayurveda mentioned in “Ashtang Ayurved”. One of them being Vrush-Chikitsa (Vajikarana Tantra). The branch deals with Alpa Shukra, Kshina Shukra, Vishushka Retasa, Utpatti, Pushthi and Vruddhi of Shukra Dhatu which can be correlated with modern terminologies such as Oligospermia, Asthenozoospermia, Teratozoospermia, Hypospermia (all are indicative of Defective Seminal parameters) along with ejaculatory defects and helps in spermatogenesis. Thus ‘Vrushya’ indicates the substance by virtue of which a person is capable to act sexually like ‘Vrisha’ (bull). Vrushya has been described as ‘Shukrajanaka’ which can be correlated to spermatogenesis. Whereas, Vajikarana is mentioned as ‘Shukra Pravartanam’ which can be defined as ejaculation which helps in the release of semen from the body. There are many Ayurvedic herbs which have the property of ‘Vrushya’. Infertility is a serious health issue worldwide, affecting approximately 8 -10% of couples worldwide. 40-50% is due to “Male factor” infertility and as many as 2% of all men will exhibit suboptimal sperm parameters. The problem of infertility exists in this day and age and one of the most prominent things of Ayurveda is that a separate branch has been mentioned in “Ashtang Ayurved”, so it is of utmost importance for us as practitioners to find the medicinal plants acting on Shukra Dhatu to tackle this problem. The attempt of this study is to highlight the plants mentioned as Vrushya in Bhavprakash Nighantu

Ab initio investigations in amorphous silicon dioxide: Proposing a multi-state defect model for electron and hole capture

Experiments as well as theoretical calculations indicate that point defects in the amorphous SiO2 layer of electronic devices as well as in optical fibers are responsible for numerous stability and reliability phenomena, including noise, hysteresis, bias temperature instabilities and decreasing transmission efficiency. In addition to the well-known oxygen vacancy, hydrogen related defects such as the hydrogen bridge and the hydroxyl-E′ center have gained a considerable amount of attention in the recent past, as they are suspected to negatively influence the device performance by capturing charge carriers from e.g. both Si and SiC substrates in field effect transistors. Here, we present a thorough ab initio study of these oxide defects and develop a unified description of electron and hole capture processes in a single multi-state model, supported by a comprehensive analysis of various defect parameters like relaxation energies, charge transition levels, (meta-)stability and transition barriers. We show that a single oxide defect can have two different trap levels for both electron and hole capturing processes, which might be the cause of anomalous device degradation phenomena. Based on its low formation energy compared to other defect types, we find that the hydroxyl-E′ center is the most promising defect candidate to explain charge capture processes in Si/SiO2 systems. Furthermore, we argue that the reduced effect of positive bias temperature instability (PBTI) observed in MOS devices compared to its negative counterpart (NBTI) can be explained by the locations of the hydroxyl-E′ centers charge transition levels.

Quantitative evaluation of deep-shallow compound defects using frequency-band-selecting pulsed eddy current testing

Deep-shallow compound defects (DSCD) may occur in both single-layer and multi-layer structures and commit great loss of structural mechanical strength. Their quantification, especially in depth, is hence imperatively required for guaranteeing the integrity and safety of engineering structures. In this paper, the defect parameters of DSCD are identified by frequency-band-selecting pulsed eddy current testing (FSPECT), and a strategy of component separation is proposed. The high-frequency component is separated from the FSPECT responses for the quantification of shallow defects so that the parameters of deep defects in DSCD can be reconstructed, which is the ultimate objective of FSPECT method. Finite element analysis (FEA) was conducted on the single-layer structure to preview the feasibility of the proposed method and to highlight the signal feature of better sensitivity. Subsequently, validation experiments were implemented on the double-layer structure and identified the features suitable for the shallow and deep defects. Besides, error propagation of the proposed method was also discussed. Results from FEA simulations and experiments show that (a) the strategy of component separation enables the quantitative evaluation of DSCD, (b) peak value (PV) should be chosen for the quantification of shallow defects while for the identification of deep defects time to zero-cross (TZC) is suggested, and (c) the deep defect can still be characterized despite the little error in the estimation of shallow defects.

Modelling the Defect Processes of Materials for Energy Applications

The technological requirement for ever more efficient materials for the energy and electronics sectors has led to the consideration of numerous compositionally and structurally complicated systems. These systems include solid solutions that are difficult to model using electronic structure calculations because of the numerous possibilities in the arrangement of atoms in supercells. The plethora of such possible arrangements leads to extensive and large numbers of potential supercells, and this renders the investigation of defect properties practically intractable. We consider recent advances in oxide interfaces where studies have demonstrated that it is feasible to tune their defect processes effectively. In this review, we aim to contribute to the ongoing discussion in the community on simple, efficient and tractable ways to realise research in solid solutions and oxide interfaces. The review considers the foundations of relevant thermodynamic models to extract point defect parameters and the special quasirandom structures method to model the supercell of solid solutions. Examples of previous work are given to highlight these methodologies. The review concludes with future directions, systems to be considered and a brief assessment of the relevant methodologies.

Influence of elevation and rainfall on leaf growth, bean characteristics and yield components of arabica and robusta coffee under changing climatic conditions in Karnataka state, India

The study was undertaken to analyze the behaviour of coffee under changing climatic conditions in different coffee liaison zones of Karnataka State, India, during 2017-2020. Sample estates were identified based on elevation and rainfall patterns in different zones of the Chikkamagaluru and Hassan districts. The leaf growth parameters, bean characteristics and yield components were recorded in all the sample estates. Correlation studies indicated a significant positive relationship between the elevation, rainfall with specific leaf area (r = +0.912) and productivity (r = 0.475) during the pre-monsoon period. The monthly summer rainfall during March and April showed a significant correlation with yield in robusta (r = 0.511) and arabica (r = 0.451), indicating that blossom shower during this period significantly influenced the productivity of coffee. The studies between elevation, the quantum of rainfall and bean defect parameters indicated a significant (p<0.05) positive correlation. A positive relationship was also found between elevation and peaberry production in both robusta (r = 0.716) and arabica coffee (r= 0.456), respectively. However, there was also a significant relationship between rainfall (2020) and Jollu percentage (r = 0.386) in robusta coffee, indicating that higher elevation and rainfall-induced more peaberry content and Jollu percentage under changing climatic conditions. The overall result indicated that changes in climatic conditions such as excess rainfall and continuous soil moisture led to more vegetative growth than reproductive growth. This also produced more bean abnormalities which in turn affected the yield and quality of the coffee.

Impact of erosion voids and internal corrosion on concrete pipes under traffic loads

The disaster testing system of buried pipes developed in this work is innovatively used to examine intact pipes, internally corroded pipes without erosion voids, and internally corroded pipes with erosion voids. The measured data are verified by the finite element models. Parametric analyses are conducted to investigate the statistical relationship between the maximum principal stress on the pipe and the defect parameters, and a multiparameter formula used to predict the maximum stress on the pipes is finally derived. The results show that the corroded pipes without erosion voids have the largest circumferential bending moment. The circumferential bending moments of the bell and spigot of the pipes with erosion voids and internal corrosion decline with an increase in the width and length of the void. The parametric sensitivity analysis demonstrates that the stress on the pipes with erosion voids and internal corrosion has a positive linear relationship with the corrosion depth, a quadratic polynomial relationship with the width and length of corrosion, and a negative linear correlation with the width and length of the void. The proposed multiparameter formula can accurately predict the maximum principal stress on the pipes with erosion voids and internal corrosion. The results fully reveal the mechanism of the combined effect of corrosion and voids on the mechanical properties of concrete pipes.

Laser damage evolution by defects on diamond fly-cutting KDP surfaces

The unavoidable surface defects on the practical processed potassium dihydrogen phosphate (KDP) crystals, especially the most common protuberance defects, which are prone to damage under intense laser irradiation, seriously limit the application of KDP optics in laser fusion facilities. In this work, a defect-induced laser damage explosion model that couples the electromagnetic field and stress field was constructed to reproduce the dynamic damage process and reveal the laser-induced damage mechanisms innovatively. First, the near-field optical modulation to incident lasers was considered to describe the effect of structural parameters of surface defects on the optical transmission performance. A multi-physics field coupled failure model was then established for the first time to explore the laser damage mechanism through the dynamic behaviors of laser damage that reproduced by this model. It was proved that the protuberance defects on KDP crystal surface would lead to severe laser damage with the characteristics of large transverse spalling and longitudinal cracks due to the Rayleigh and stress waves, which well agrees with the results of laser damage experiments. The established damage model is capable of revealing the hazards of protuberance defects, and providing effective guidance for the suppression of surface defects introduced in the optical ultra-precision machining processes.

Photocatalytic CO2 Conversion Using Anodic TiO2 Nanotube-CuxO Composites

Nanosized titanium dioxide (TiO2) is currently being actively studied by the global scientific community, since it has a number of properties that are important from a practical point of view. One of these properties is a large specific surface, which makes this material promising for use in photocatalysts, sensors, solar cells, etc. In this work, we prepared photocatalysts based on TiO2 nanotubes for converting carbon dioxide (CO2) into energy-intensive hydrocarbon compounds. Efficient gas-phase CO2 conversion in the prepared single-walled TiO2 nanotube-CuxO composites was investigated. Parameters of defects (radicals) in composites were studied. Methanol and methane were detected during the CO2 photoreduction process. In single-walled TiO2 nanotubes, only Ti3+/oxygen vacancy defects were detected. The Cu2+ centers and O2− radicals were found in TiO2 nanotube-CuxO composites using the EPR technique. It has been established that copper oxide nanoparticles are present in the TiO2 nanotube-CuxO composites in the form of the CuO phase. A phase transformation of CuO to Cu2O takes place during illumination, as has been shown by EPR spectroscopy. It is shown that defects accumulate photoinduced charge carriers. The mechanism of methane and methanol formation is discussed. The results obtained are completely original and show high promise for the use of TiO2-CuxO nanotube composites as photocatalysts for CO2 conversion into hydrocarbon fuel precursors.